144 ANNUAL OF SCIENTIFIC DISCOVERY. 



the platinum wire itself, by the calorific effect exhibited on the fusion of 

 the platinum wire. These researches are now preparing for publication in 

 the Professional Papers of the Corps of Engineers. Proc. British Associ- 

 ation. 



ON THE APPARENTLY MECHANICAL ACTION ACCOMPANYING ELEC- 

 TRIC TRANSFER. 



Mr. A. Crosse, in a paper before the British Association, stated that he 

 had found that by electrifying a sovereign positively in close contact with 

 a piece of carbonate of lime, under nitric acid diluted with fifty times its 

 quantity of water, that a portion of the milled edge of the coin was struck 

 off in pieces, some of which were large enough to retain the milled edge 

 upon them distinctly. The voltaic action was kept up for fifty hours ; 

 and at the expiration of that time the coin had lost three grains in weight, 

 and a ground glass rod that was used to keep the coin in contact with the 

 limestone was permanently gilded ; and this took place at the positive 

 pole. The weight of the portions removed from the coin exactly corre- 

 sponded with the deficiency. The solution being tested contained nitrate 

 of lime, but no gold or copper. I likewise found on repeating this 

 experiment with sulphuric acid, similarly diluted the voltaic action being 

 kept up for ninety hours that six grains of gold were removed from the 

 edge of the coin ; and the pieces broken off weighed the same. A strip 

 of glass being placed on the edges of the jar containing the dilute acid, 

 and half an inch above its surface, and in a line with the electric current, 

 had its lower part covered with crystals of sulphate of lime, each one of 

 which was at right angles to the electric current. The friction of the 

 carbonic acid gas liberated from that part of the limestone in contact with 

 the coin was apparently the mechanical cause of the removal of the 

 edges. The author stated that he had tried various experiments both 

 with frictional and voltaic electricity upon different substances, which in 

 his opinion proved the effects of the mechanical action accompanying 

 electric transfer. 



ON THE ORIGIN OF THE AURORA BOREALIS. 



M. de la Rive, the celebrated Genevan natural philosopher, has recently 

 published a long memoir on the Aurora Borealis, and which he has 

 attempted to account for, and apparently with success. Perhaps no 

 phenomenon in the world is more beautiful than " these magnetic tem- 

 pests," (Von Humboldt,) which in the Arctic regions fill the heavens 

 with a sea of flame. M. de la Rive attributes them to electro-magnetic 

 causes. The terrestrial globe, he says, uniformly acts as a large magnet, 

 and its magnetic poles do not coincide with its poles of rotation ; further- 

 more, the atmosphere is continually charged with positive electricity, 

 which is accumulated in its superior regions, and this electricity (whether 



